Summer is here and so is our extensive collection of hydrangeas. At Madison Square Park, there are over 300 individual hydrangea plants, most of them fall into five of the species commonly grown in gardens.
Hydrangea macrophylla, the bigleaf hydrangea, is perhaps the quintessential hydrangea. This is the most widely known hydrangea, and is the kind most people know for its ability to change flower colors depending on the pH of the soil. Acidic soils release aluminium ions which are responsible for the blue color of bigleaf hydrangeas. In alkaline soils, aluminum is not found so the hydrangeas will display bright pink colors. At the sweet spot of mildly acidic to neutral soils, bigleaf hydrangeas will display either a mix of blue and pink flowers or a brilliant violet.
Hydrangea paniculata, the panicled hydrangea, is one of the more winter hardy hydrangeas. This shrub produces long branches topped with pyramidal flower clusters called panicles. These panicles, which come in white, pink, or green, often cause the stems to bend downwards, giving the plants a graceful arching.
Hydrangea arborescens, the smooth hydrangea, is one of the two species native to the U.S. It blooms on new wood, so it is often pruned down to the ground yearly to revitalize the plant and ensure a strong floral display. The cultivar ‘Annabelle’ has large balls of white, sterile flowers, similar to the mophead bigleaf hydrangeas.
Hydrangea quercifolia, the oakleaf hydrangea, produces panicles similar to the panicled hydrangea. Oakleaf hydrangeas, as their name implies, possess leaves with lobes that give them the appearance of a large oak leaf––they are also a native species to the U.S.
Hydrangea anomala, the climbing hydrangea, is a large woody vine. This species is not as showy as the subspecies petiolaris, which is invariably the climbing hydrangea that nurseries often have available. Aside from their vining nature, climbing hydrangeas are noted for their exfoliating bark when mature.